Polymer (Kimberly Tafoya)

Author

Principle(s) Illustrated

Standard

2a) Students know large molecules (polymers), such as proteins, nucleic acids, and
starch, are formed by repetitive combinations of simple subunits.

10b) Students know chemical bonds between atoms in molecules such as H2, CH4, NH3,
H2CCH2, N2, Cl2, and many large biological molecules are covalent.

Questioning Script

Prior knowledge & experience:

Root question:

What will happen when you mix a polymer with water?

Target response:

The crystals are probably coming from the "super absorbent layer" found in most disposable diapers. This layer consists of paper fluff and a chemical absorbent called sodium polyacrylate. Sodium polyacrylate is an amazing water absorber -- it can absorb 200 to 300 times its weight in tap water (even more if the water is distilled) and hold it in a gooey gel.

Sodium polyacrylate is a polymer, meaning that it consists of chains of identical units (monomers). The monomer for sodium polyacrylate is:

--CH2--CH(CO2Na)--

It is a pretty cool polymer -- shake the crystals out of a new diaper (or buy the crystals at a garden center) and add water to them. Pretty amazing!